Repeated DNA in primates, especially in humans, will be examined by specific restriction endonuclease cleavage, by DNA sequencing and by in situ hybridization. Experiments will be designed to decide whether tandemly-repeated DNA provides genetic flexibility for driving speciation. Specifically, we will study the involvement of newly-evolved, tandemly-repeated DNA in karyotype evolution and in the formation of karyotypic abnormalities in cancer cells. We will attempt to determine how repeated DNA is involved in recombinational processes, such as unequal crossing over. Experiments will also be designed to elucidate the mechanism by which repeated DNA becomes interspersed among nonrepeated DNA. We will determine the nucleotide sequence of interspersed, repeated DNA and of its flanking sequences. Over the long term we are interested in knowing whether repeated DNA carries recombination-promoting domains that mediate gene mobility.